One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(6,8)(13,14)(15,21)(16,24)(17,18)(19,22)(20,25)(23,26)(27,28)(2,3)(10,12)(14,18)(15,22)(16,25)(26,27) involution — undirected(9,10,11,12)(13,15)(14,19)(16,23)(17,22)(18,21)(20,26)(24,27)(25,28)(2,3)(5,6)(7,8)(13,14)(15,19)(16,24)(17,18)(20,25)(21,22)(23,27)(26,28) involution — undirected(1,3,4,2)(13,16)(14,20)(15,23)(17,25)(18,24)(19,26)(21,27)(22,28)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.